Depth data, for use in the ‘image plus depth’ format, may be imperfect. For example, the depth data may be generated by a so-termed 2D-to-3D conversion, in which the input image data is used as a basis for estimating the depth data. Such estimating may be incorrect at times, causing artifacts to appear in the depth data, which, after viewpoint generation, may cause artifacts becoming visible in the displayed 3D scene. Such artifacts may also appear when using a so-termed stereo-to-depth conversion, in which a stereo image pair is used as a basis for generating the depth data. WO 2007/132397-A2 discloses an example of a 2D-to-3D conversion process. The 2D-to-3D conversion and stereo-to-depth conversion processes are examples of depth data generation processes.
For reducing artifacts that are present in a depth map, a publication “Boundary-Based Depth Image Improvement” by Yang-Keun Ahn et al., in “Advances in Visualization, Imaging and Simulation”, November 2010, discloses use of median filters to remove noise from the depth map for improving a subsequent depth-based image rendering.